What is Energy? Energy is an extremely difficult concept to define in physics, because it is evident in many diverse forms. Energy is important to us as humans, because energy is an integral part of our lives. Humans have a great dependence on energy, for example electrical energy, which delivers the necessary energy to run appliances. Radiant energy, such as energy in heat and light from the sun, and chemical energy, such as that which is obtained from the breakdown of proteins in our digestive system, are also forms of energy that are relevant to our lives. Energy applied to as a force over a distance is defined as work, which is measured in joules. One joule of work is the amount of force required to move an object of a mass of one kilogram per one meter. An amount of work done over a specific time period is known as power. Mechanical energy exists in several primary forms: gravitational potential energy, kinetic energy, and elastic potential energy. One of the most important concepts regarding energy is the fact that energy cannot be created of destroyed, which is known as the Law of Conservation of Energy. [3][4][5][6][7][8][9]
Vocabulary
Energy - a thermodynamic quantity that is the capacity of a system of forces to do work
Work - the transfer of energy from one object, system, or source of energy to another, for which the SI unit is joules(J=N•m=kg•m/s/s)
Power - The work done over a certain amount of time, which is expressed in SI units as the watt(W=J/s)
Mechanical Energy - It is the sum of the conservative forces of energy in a system
Potential Energy - the mechanical energy possessed by a mass due to position
Kinetic Energy - the mechanical energy possessed by a mass due to motion
Efficiency - The relation between the input of energy to the output of energy into a system
Law of Conservation of Energy - the first law of thermodynamics-it states that the energy within a system will remain constant, as long as no external force act upon it
Machine - a device which transfers energy from one form to another in order to perform a certain task
Lever - a rigid bar pivoted about a fulcrum
Pulley - a simple machine consisting of a rope and a wheel that changes the direction or point of application of an applied force
Thermodynamics - the physics that involve the conversion of different forms of energy.
The Law of Conservation Energy and Gravitational Potential Energy
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Energy is always conserved during any transform or process. Energy may be converted into many types or forms, but it is never created or destroyed. Energy cannot instantaneously appear or vanish without a trace. For example, as you turn the knob on a wind up toy, energy becomes stored in the spring and it becomes potential energy. When released, the toy is set into motion, transforming the energy into kinetic energy and energy lost from the system in the form of light, sound, and friction. Another example is when one draws back a bow and releases it to fire an arrow. This is all part of the Law of Conservation Energy, which states that energy remains constant and cannot be created or destroy; it can only be converted or transformed to another type of energy. Energy may change forms but its total amount never changes. The Law of Conservation Energy states that energy in this universe will stay constant; there is no more or less energy in the universe now than there ever was or ever will be. Another name than The Law of Conservation Energy is Thermodynamic First Law. Thermodynamics is another branch of physics that deals with energy. [3][6][7]
This video displays how all the energy is conserved in the system through The Law of Conservation Energy.
Work and Kinetic Energy
Work, what is it? Is it going to work at job, doing your homework, or reading this? Or is it just a person holding a set of heavy weights in their hands and just standing there? No, In terms of physics, it is a force applied over a distance; therefore, work equals force times distance or W=Fd. The SI Unit to measured work is Joule or J, expressed in Newton-meters. Work is a scalar quantity, meaning it has no direction. A person that is holding a set of heavy weights, standing still is doing no work, but if they began lifting the weights it would be considered work. Kinetic Energy is motion that enables work. The work-energy theorem states that the net work done on an object is equal to the change in the object's kinetic energy. [1][2][3][5][9]
Elastic Potential Energy
Elastic Potential Energy, also known as Spring Potential Energy, regards the forces created by the stretching and compressing of a spring. When a spring is in equilibrium the EPE is equal to zero, but as it undergoes a displacement the forces acting on it increase or decrease, depending on the magnitude of the displacement. This is known as Hooke's Law, represented by the equation Fs=-kx.
Power
Power is defined as the amount of work done on a system in a certain amount of time. The Equation for Power is power equals work divided by time and the SI unit is the Watt, or Joule per second (J/s). The United States unit for Power is called horsepower, and 746 watts equal 1 horsepower. [1][2][3]
Energy
Table of Contents
Vocabulary
The Law of Conservation Energy and Gravitational Potential Energy
This video displays how all the energy is conserved in the system through The Law of Conservation Energy.
Work and Kinetic Energy
Work, what is it? Is it going to work at job, doing your homework, or reading this? Or is it just a person holding a set of heavy weights in their hands and just standing there? No, In terms of physics, it is a force applied over a distance; therefore, work equals force times distance or W=Fd. The SI Unit to measured work is Joule or J, expressed in Newton-meters. Work is a scalar quantity, meaning it has no direction. A person that is holding a set of heavy weights, standing still is doing no work, but if they began lifting the weights it would be considered work. Kinetic Energy is motion that enables work. The work-energy theorem states that the net work done on an object is equal to the change in the object's kinetic energy. [1][2][3][5][9]
Elastic Potential Energy
Elastic Potential Energy, also known as Spring Potential Energy, regards the forces created by the stretching and compressing of a spring. When a spring is in equilibrium the EPE is equal to zero, but as it undergoes a displacement the forces acting on it increase or decrease, depending on the magnitude of the displacement. This is known as Hooke's Law, represented by the equation Fs=-kx.
Power
Power is defined as the amount of work done on a system in a certain amount of time. The Equation for Power is power equals work divided by time and the SI unit is the Watt, or Joule per second (J/s). The United States unit for Power is called horsepower, and 746 watts equal 1 horsepower. [1][2][3]
Reference